En Route to Jupiter and Saturn from 29 Jun 2009 through 3 Jul 2009

En Route to Jupiter and Saturn

SCIENTIFIC REPORT

Goals of the workshop

After successful missions to Titan, Mars, and Venus, the
European Space Agency (ESA) has plans to embark on another planetary mission.
Following ESAís Cosmic Vision call for plans for
space missions to be launched in the 2015-2020 timeframe, planetary scientists
in Europe and elsewhere collaborated on writing several mission proposals. In
close collaboration with NASA, ESA selected from these proposals two large
missions that it thought to be interesting: one to Jupiter and two of the
Galilean moons, and the other to Saturn and its largest moon, Titan. In the
spring of 2009, ESA and NASA announced that the Jupiter mission, now called the
Europa-Jupiter-System-Mission (EJSM), had their
priority, and that the Saturn mission, the Titan-Saturn-System-Mission (TSSM),
might be launched later.

In this workshop, we brought together scientists from both
missions to identify and discuss the missionsí science cases and instruments.
The focus of the workshop was EJSM, because this mission has been prioritized
and will likely play a major role in planetary sciences for decades to come.
Fostering collaborations between planetary scientists from the different
missions (note that some scientists were involved in both msissions)
is not only important for improving the scientific output of the mission, but
it is also essential for the next phase of ESAís
selection procedure: EJSM still has to be approved for launch.

Workshop participants

Besides planetary scientists from several European countries, we
also invited Dutch scientists that are currently working in the field of Earth
Sciences, in order to stimulate their interest in the growing field of
Planetary Sciences in the Netherlands and to improve the exchange of knowledge
between the two fields. Furthermore, students that take courses on Planetary
Sciences in the Netherlands were encouraged to attend the workshop, in order to
increase their enthusiasm for the field by confronting them with outstanding
scientific questions and with the several technical issues surrounding the
development of planetary missions.†

Description of the
missions to Jupiter and Saturn

The Europa-Jupiter-System-Mission will
consist of two spacecraft that will each start their exploration of the Jovian system
(after arriving around 2026) by orbiting the gas giant Jupiter for several
months. Then, NASAís Jupiter-Europa Orbiter (JEO)
will get into orbit around the moon Europa, while ESAís Jupiter-Ganymede orbiter (JGO) will start orbiting
the moon Ganymede. The missionís science objectives for Jupiter itself are to
study the composition, structure, chemistry, and dynamics of the planetary atmosphere, and the structure of the planetís huge magnetic
field and associated intense radiation field. The scientific interest in Europa is mainly driven by the layer of water ice that
completely covers this large moon. There are indications of an ocean of liquid
water below this ice layer, and astrobiologists have
argued that this ocean might harbor life. Ganymede, a moon that is larger than
our own moon, is the only moon with a magnetosphere, which hints at the
presence of subsurface liquid layers, and has striking surface features that
could be caused by tectonic activity.

The Titan-Saturn-System-Mission would consist of a spacecraft to
orbit Saturn, and a montgolfiere (a hot air balloon),
that would float for months through the thick atmosphere of the moon Titan. The
scientific objectives of the Saturn orbiter would be to study the atmospheric
composition, structure, chemistry, and dynamics. From the instrumentation
tethered to the balloon, the composition, structure, chemistry, and dynamics of
Titanís atmosphere would be studied and they would offer the opportunity to
observe and map the moonís surface, which is hidden from observers on Earth and
in space by a thick, photochemical smog.††

Workshop program

Because of the broad scientific objectives of the Jupiter and
Saturn missions, the workshop program covered various topics, spread over the
week:

The last day was spent on summarizing the results from the
workshop, on discussing the open scientific issues for the Europa-Jupiter-System-Mission
and the Titan-Saturn-System-Mission.

Concluding remarks

Few of the international participants had known about the
Lorentz Center before the workshop. They as well as the other participants were
very enthusiastic about the available facilities and the excellent assistance
of the Lorentz Center staff. The atmosphere at the workshop was very relaxed
and fruitful.

Acknowledgements

The organizers are very grateful to the Lorentz Center staff
that supported the workshop, to the financial sponsors of the Lorentz Center,
and to TNO, DutchSpace, NSO, and SRON Netherlands
Institute for Space Studies for the additional financial support.